Flagstone laid in manufactured sand

by Bill
(vermont )

i perpared the patio area using manufactured sand. leveled patio area with 2 to 3 inch of compacted sand.` i laid and leveled the the flagstones, than packed manufactured sand around the stones. i have watered and tamped area repeatedly and sand does not seem to be compacting between the stones.

Question: is there an type of product perferrably liquid that i pour between the stones that will harden hold the stones?